Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium–fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and 11B nuclear magnetic resonance studies suggest that co-intercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties

Pyrite-induced hydroxyl radical formation and its effect on nucleic acids

BACKGROUND: Pyrite, the most abundant metal sulphide on Earth, is known to spontaneously form hydrogen peroxide when exposed to water. In this study the hypothesis that pyrite-induced hydrogen peroxide is transformed to hydroxyl radicals is tested. RESULTS: Using a combination of electron spin resonance (ESR) spin-trapping techniques and scavenging reactions involving nucleic acids, the formation of hydroxyl radicals in pyrite/aqueous suspensions is demonstrated. The addition of EDTA to pyrite slurries inhibits the hydrogen peroxide-to-hydroxyl radical conversion, but does not inhibit the formation of hydrogen peroxide. Given the stability of EDTA chelation with both ferrous and ferric iron, this suggests that the addition of the EDTA prevents the transformation by chelation of dissolved iron species. CONCLUSION: While the exact mechanism or mechanisms of the hydrogen peroxide-to-hydroxyl radical conversion cannot be resolved on the basis of the experiments reported in this study, it is clear that the pyrite surface promotes the reaction. The formation of hydroxyl radicals is significant because they react nearly instantaneously with most organic molecules. This suggests that the presence of pyrite in natural, engineered, or physiological aqueous systems may induce the transformation of a wide range of organic molecules. This finding has implications for the role pyrite may play in aquatic environments and raises the question whether inhalation of pyrite dust contributes to the development of lung diseases

Ammonia Treatment of 0.35Li₂MnO₃·0.65LiNi_0.35Mn_0.45Co_0.20O₂ Material: Insights from Solid-State NMR Analysis

Li-rich cathode materials of the formula <i>x</i>Li₂MnO₃·<i>y</i>LiNi_<i>a</i>Co_<i>b</i>Mn_<i>c</i>O₂ (<i>x</i> + <i>y</i> = 1, <i>a</i> + <i>b</i> + <i>c</i> = 1) boast very high discharge capacity, ca. 250 mAh/g. Yet, they suffer capacity decrease and average voltage fade during cycling in Li-ion batteries that prohibit their commercialization. Treatment of the materials with NH₃(g) at high temperatures produces improved electrodes with higher stability of capacity and average voltage. The present study follows the changes occurring in the materials upon treatment with ammonia gas, through ⁶Li and ⁷Li solid-state NMR investigations of the untreated and ammonia treated 0.35Li₂MnO₃·0.65LiNi_0.35Mn_0.45Co_0.20O₂ as well as its constituent phases, Li₂MnO₃ and LiNi_0.4Co_0.2Mn_0.4O₂. The NMR analysis demonstrates the biphasic nature of these materials. Furthermore, it shows that the Li₂MnO₃ component phase in the integrated material is the phase mostly being affected by the gas treatment. A thickening of a protective surface film in the integrated material, with the right exposure time to the reactive gas, is observed, which further precludes Ni leach out from the bulk and leads to improved electrode performance. Formation of minor electrochemically inactive oxide phases in the integrated material and similarly in the Li₂MnO₃ alone upon longer exposure to the gas suggests that the performance deterioration observed can be linked to the rearrangement of ions in the Li₂MnO₃ constituent phase in the integrated material

Medical student education program in Alzheimer’s disease: <it>The PAIRS Program</it>

<p>Abstract</p> <p>Background</p> <p>As life expectancy increases, dementia incidence will also increase, creating a greater need for physicians well-trained to provide integrated geriatric care. However, research suggests medical students have limited knowledge or interest in pursuing geriatric or dementia care. The purpose of this study is to evaluate the <it>PAIRS Program</it> and its effectiveness in enhancing medical education as a service-learning activity and replication model for the Buddy Program^TM.</p> <p>Methods</p> <p>Between 2007 and 2011, four consecutive classes of first year Boston University School of Medicine students (n = 45; 24 ± 3 years, 58% female, 53% White) participated in a year-long program in which they were paired with a patient with early-stage Alzheimer’s disease (AD). Assessments included pre- and post-program dementia knowledge tests and a post-program reflective essay.</p> <p>Results</p> <p>Program completion was 100% (n = 45). A paired-sample <it>t</it>-test revealed a modest improvement in dementia knowledge post-program (p < 0.001). Using qualitative coding methods, 12 overarching themes emerged from the students’ reflective essays, such as observing care partner burden, reporting a human side to AD, reporting experiences from the program that will impact future clinical practice, and obtaining a greater understanding of AD.</p> <p>Conclusions</p> <p>Quantitative and qualitative findings suggest that the <it>PAIRS Program</it> can enhance the acquisition of knowledge, skills, and positive attitudes regarding geriatric healthcare in future generations of physicians, a skill set that is becoming increasingly relevant in light of the rapidly aging population. Furthermore, results suggest that The Buddy Program^TM model can be successfully replicated.</p